Selenium is one of the 15 kinds of essential trace elements, and exerts an anti-tumor activity, an antioxidation activity, an anti-aging activity, an immune enhancing activity, a protection and restoration effect on cells, an antagonistic effect to reduce harmful heavy metals and other important biological activities in vivo. Occurrence and development of up to 40 types of diseases, including AIDS, liver cancer, Keshan disease, Kashin-Beck disease, and cardiovascular and cerebrovascular diseases, is closely associated with selenium deficiency.
For those with a low level of selenium or selenium deficiency, supplementation of an appropriate amount of selenium can enhance immunity, maintain the normal functions of vital organs such as heart, liver, lung and stomach, and prevent the occurrence of tumors, liver diseases and cardiovascular and cerebrovascular diseases. More than 40 countries belong to selenium deficient areas globally, and several provinces in China are part of selenium deficient zones or low-level selenium zones, and the incidence of tumors, liver diseases and cardiovascular and cerebrovascular diseases are high in these areas and zones, so people in these areas and zones need to be supplemented with selenium.
However, as a nutritional supplement or a cancer preventing agent, the range between a beneficial dose and a toxic dose of selenium is very narrow, such that selenium poisoning occurs easily, which severely limits the potential application of selenium in the prevention and treatment of diseases, especially in the prevention and treatment of cancers. The toxicity of selenium depends on the chemical form thereof, and the current study results find that the toxicity of inorganic selenium compounds is stronger than that of organic selenium compounds, the toxicity of selenocysteine is similar to that of sodium selenite, and the toxicity of sodium selenite is stronger than that of nano-selenium. Nano-selenium has the advantages of high bioavailability, high biological activity and low toxicity.
Nano-elemental selenium is usually prepared by a reduction method where an oxysalt or oxide of selenium is reduced by various reducing agents to obtain the elemental selenium, and at the same time, the morphology is modified or regulated by using a modifier or a regulating agent in order to obtain a product with desired particle size and morphology.
Endeavours in the field include that by Zhang Jinsong et al., (Chinese Patent application publication no. CN1184776A), in which was disclosed the use of a reducing agent in protein or peptide solution system to reduce the protein or peptide controlled nano-selenium selenium compounds, whereby solid nano elemental selenium is obtained following separation and drying.
Other patent literature include Chinese patent application publication no. CN1415241A “Glucomannan nano-selenium and the preparation method thereof”, Chinese patent application publication no. CN415309 A “Melatonin nano-selenium and the preparation method thereof”, Chinese patent application publication no. CN1415310 A “Chitin nano-selenium and the preparation method thereof”, Chinese patent application publication no. CN1415308 A, “Amino acid nano-selenium and the preparation method thereof” and Chinese patent application publication no CN1789113 A), “A method for preparing nano-selenium sol.”
Other endeavours include Chinese patent application publication no. CN1947723 A “A liquid polysaccharide nano-selenium and the preparation and storage thereof”; Chinese patent application publication no. CN100998603 A “Liquid vitamin C complex nano elemental selenium and the preparation and preservation methods thereof” and Chinese patent application publication no CN101040869 A “Liquid amino acid coupled elemental nano-selenium and the preparation and preservation methods thereof patent.” Within the scientific literature those by Huang Liang et al. (Chemical Journal of Chinese Universities [J], 2007, 28 (2): 208 to 211) which discloses polysaccharides of Undaria pinnatifida or an oxidative degraded product thereof as effective in modifying and stabilizing nano-selenium; and by Zhang et al (Langmuir [J], 2010, 26 (22): 17 617 to 17623) which discloses that the many of the multi-branched polysaccharides display good control effect on the morphology and particle size of nano elemental selenium.